Fortigate SIP Problem (or Portchange without NAT)

Hello,

i have a fortigate 500 with FortiOS 5.4.6 on it.

The Firewall works since over 2 years, but since friday i have the problem, that one Port change the destination port.

Normally the policy (and static route) says: all traffic destination xx.xxx.62.3 goes over vpn to destination (Source und Destination Port 5060). Now or since friday comes the traffic on source port 5060 and goes out at 15060.

The traffic now not goes in the VPN TUnnel, and directly into the wan and was blocked by policy violation.

What can i do, to fix the problem.

Interestingly it works between, without make a change at the firewall.

Thanks for any advise and kind regards

Tobias